1. Field of the Invention
The present invention relates to a processing jig for holding an object processed by a processing apparatus.
2. Description of the Related Art
A flying-type thin-film magnetic head used for a magnetic disk device and so on is generally made up of a slider and a magnetic head element provided at the trailing edge of the slider. The slider generally comprises a rail whose surface functions as a medium facing surface (an air bearing surface) and a tapered section or a step near the end on the air inflow side. The rail flies slightly above the surface of a recording medium such as a magnetic disk by means of air flow from the tapered section or step.
A thin-film magnetic head element generally used is a composite-type element made up of layers of an induction-type electromagnetic transducer for writing and a magnetoresistive (MR) element for reading.
In general, such thin-film magnetic heads are formed through cutting a wafer in one direction in which sections to be sliders (hereinafter called slider sections) each including a thin-film magnetic head element are aligned in a plurality of rows. A bar-like magnetic head material (hereinafter called a bar) made up of a row of slider sections is thereby formed. Processing such as lapping is performed on a surface of the bar to be the medium facing surface (hereinafter called the medium facing surface for convenience). The bar is then separated into individual sliders.
In general, in order to stabilize the output characteristic of a thin-film magnetic head, it is important to maintain the distance between the magnetic pole of the head and the surface of a recording medium at an extremely small specific value. It is therefore required in magnetic head processing that the flatness of the medium facing surface of the head precisely fall on a specific value so as to stabilize a flying amount and that the throat height and the MR height of the head fall within a specific range. The throat height is the length (height) of the magnetic pole of an induction-type electromagnetic transducer between an end thereof located in the medium facing surface and the other end. The MR height is the length (height) between an end of the MR element located in the medium facing surface and the other end.
There are several methods for lapping the medium facing surface so as to achieve desired values of the throat height and MR height of a thin-film magnetic head. A method generally used and achieving high precision is the method that utilizes a processing jig having functions described later and a lapping apparatus having the function of automatically lapping while applying an appropriate load to the jig and deforming the bar bonded to the jig.
The processing jig used in this method comprises a main body fixed to the lapping apparatus, a retainer that is long in one direction for retaining a bar, and a plurality of load application sections, coupled to the retainer, to each of which a load is applied for deforming the retainer. The shape of the retainer is a narrow and long beam that is bent with an application of external force. An external force being applied to the load application sections of the jig, the retainer is bent. The bending of the retainer causes bending of the bar held by the retainer.
A method of lapping a bar using the jig will now be described. In this method, the bar is fixed to the retainer of the jig with an adhesive and the like so that the surface of the bar to be lapped faces outside.
Next, the values of the throat height and MR height of each magnetic head element in the bar fixed to the jig are determined through an optical or electrical method. The deviation of the determined values from the target values, that is, the amounts of lapping required, are calculated.
Of the sections to be lapped corresponding to the magnetic head elements in the bar, a section that requires a greater amount of lapping than the other sections needs to be more lapped. Therefore, the bar is deformed by applying a load to the load application sections so that the surface to be lapped of the section is made convex. On the other hand, a section that requires a smaller amount of lapping than the other sections needs to be less lapped. Therefore, the bar is deformed by applying a load to the load application sections so that the surface to be lapped of the section is made concave. The bar is lapped by pressing the medium facing surface of the bar against a rotating lapping plate while the bar is deformed.
In such a manner, a series of operations is automatically repeated, including determining the throat height and the MR height of each magnetic head element, calculating the deviation of the determined values from the target values, that is, the amounts of lapping required, and lapping the bar while deforming the bar in accordance with the amounts of lapping required. Variations in the throat heights and the MR heights of the magnetic head elements are thereby modified. Finally, the throat heights and the MR heights of the magnetic head elements fall within a specific range.
A lapping apparatus for performing lapping of a bar as described above is disclosed in U.S. Pat. No. 5,620,356. A jig for lapping magnetic heads is disclosed in U.S. Pat. No. 5,607,340. A lapping control apparatus is disclosed in Published Unexamined Japanese Patent Application Heisei 2-95572 (1990) for controlling the throat height through observing a resistance of an MR element.
In prior art a bar of a specific length is separated from a wafer, and processing such as lapping is performed on the bar through the use of a processing jig as the one described above.
It is preferred to utilize a bar as long as possible in order to increase the processing efficiency, that is, to maximize the number of products obtained through processing at a time. Therefore, it is required to change the length of the bar in some cases. It is possible in such a case to change the length and height of the processing jig in accordance with the bar length.
However, the processing jig is used in a plurality of steps in addition to lapping. In each of these steps the jig is aligned and fixed when used. Therefore, if the length or the height of the jig is changed, it is required to change all of the portions used for alignment and fixing of the jig in each of the steps. In addition, if some types of processing jigs having different length or height are used, it is required to design the portions used for alignment and fixing of the jig such that these portions conform to the different types of jigs in each of the steps. Taking these factors into account, it is desirable that the shapes of the jigs are the same, regardless of the bar length.
However, in the prior-art processing jig as the one disclosed in U.S. Pat. No. 5,607,340 mentioned above, the ends of the retainer are coupled to the main body. In the jig having such a structure, flexible deformation of the neighborhoods of the ends of the retainer is suppressed. Therefore, it is difficult to deform the neighborhoods of the ends of the retainer, in particular, of the prior-art jig into a desired shape. Consequently, the prior-art jig has a problem that, if the bar length is long, the deviations from the target values of the throat height and the MR height of each of thin-film magnetic head elements increase, the elements being located near the ends of the bar.
It is an object of the invention to provide a jig having a retainer for retaining an object to be processed that is long in one direction, the jig deforming the object by deforming the retainer, the jig being capable of deforming the retainer including portions near ends thereof into a desired shape and processing the object with accuracy even if the object is long.
A processing jig of the invention retains an object to be processed that is long in one direction. The jig is fixed to a processing apparatus for processing the object. The jig comprises: a main body to be fixed to the processing apparatus; a retainer that is long in one direction for retaining the object; a plurality of couplers for coupling the retainer and the main body to each other; and a plurality of load application sections to each of which a load is applied for deforming the retainer, the load application sections being coupled to the retainer. Both ends of the retainer are not coupled to the main body but left open.
According to the jig of the invention, since the ends of the retainer are not coupled to the main body but left open, it is possible to deform the retainer including portions near the ends thereof into a desired shape.
According to the processing jig of the invention, each of two of the load application sections may be located closer to each of the ends of the retainer than a middle of the length of the retainer, and coupled to a position closer to the middle by a specific distance from each of the ends of the retainer. In addition, each of two of the couplers may have an end connected to the main body and the other end connected to a portion coupling each of the two of the load application sections to the retainer. In this case, each of the two of the couplers may be plate-shaped and flexible.
According to the processing jig of the invention, the object may be a bar-like magnetic head material made up of a row of sections to be sliders each of which includes a thin-film magnetic head element.
Other and further objects, features and advantages of the invention will appear more fully from the following description.